Analysis of aneuploidy for chromosomes 13, 21, X and Y by multicolour fluorescence in situ hybridisation (FISH) in a 47,XYY male

The frequency of aneuploid sperm was assessed by fluorescence in situ hybridisation (FISH) in a 47,XYY male previously studied by sperm karyotyping. A total of 20,021 sperm were studied: 10,017 by two-colour FISH for chromosomes 13 and 21 and 10,002 by three-colour FISH for the sex chromosomes using chromosome 1 as an autosomal control for diploidy and lack of hybridisation. Results were compared with more than 500,000 sperm from 18 normal men. The frequencies of X-bearing (49.4%) and Y-bearing sperm (49.8%) were not significantly different from 50% as shown in our sperm karyotyping study. There was no significant increase in the frequency of diploid sperm compared with control donors. There was a significant increase in the frequency of disomy for chromosome 13 (p < 0.0001) and XY disomy (p = 0.0008) compared with control donors. However, since the frequency of disomy was 0.40% for chromosome 13 and 0.55% for XY disomy, it is not surprising that these increases were not discovered previously in our analysis of 75 sperm karyotypes. Our results suggest that the extra Y chromosome is eliminated during spermatogenesis in the majority of cells but that there may be a small but significant increase in the frequency of aneuploid sperm in these men.

Analysis of sperm chromosome complements before, during, and after chemotherapy

Sperm chromosomal abnormalities were assessed in testicular cancer patients before, during, and after BEP (bleomycin, etoposide, cisplatin) chemotherapy (CT). Multicolor fluorescence in situ hybridization (FISH) analysis was employed to detect aneuploidy for chromosomes 1, 12, X, and Y, and diploidy. Sperm samples were cryopreserved and coded before analysis to facilitate "blind" analysis. Complete results at all time points was available for only one patient. A total of 60,400 sperm were analyzed: 20,004 before CT, 20,005 during CT, and 20,391 after CT. There was a significant increase in the frequency of 24,XY sperm during (0.33%) and post-CT (0.34%) compared to pre-CT (0.14%). This study suggests that there may be a significantly increased risk of chromosomal abnormalities in sperm of CT patients during and immediately post-CT, similar to that shown in animal models.

Abnormalities for chromosomes 13 and 21 detected in spermatozoa from infertile men

Sperm samples from infertile men with oligozoospermia or teratozoospermia were studied by multicolour fluorescence in-situ hybridization (FISH) using DNA probes for chromosomes 13 and 21. A total of 90 809 sperm nuclei from nine infertile men and 182 799 sperm nuclei from 18 control donors were analysed. There was a highly significant increase in the frequency of spermatozoa disomic for chromosome 13 in infertile patients (0.28%) compared to control donors (0.13%) (two-tailed Z statistic P < 0.0001) and for chromosome 21 (0.48% in infertile men versus 0.37% in controls, P < 0.0001). Also there was a significantly increased frequency of diploid spermatozoa in infertile men (0.85%) compared to control donors (0.66%) (P < 0.0001). Our previous studies on these same infertile patients demonstrated increased frequencies of sperm disomy for chromosomes 1 and XY. This suggests that infertile men, who are prime candidates for intracytoplasmic sperm injection, may be at a very small increased risk of aneuploid offspring.

Direct evidence for suppression of recombination within two pericentric inversions in humans: a new sperm-FISH technique

Crossover within a pericentric inversion produces reciprocal recombinant chromosomes that are duplicated/deficient for all chromatin distal to the breakpoints. In view of this fact, a new technique is presented for estimating the frequency of recombination within pericentric inversions. YAC probes were selected from within the q- and p-arm flanking regions of two human inversions, and two-color FISH analysis was performed on sperm from heterozygous inversion carriers. A total of 6,006 sperm were analyzed for chromosome 1 inversion (p31q12), and 3,168 were analyzed for chromosome 8 inversion (p23q22). Both inversions displayed suppression of crossing-over, although the amount of suppression differed between the two inversions. The recombination frequency of 13.1% recorded for chromosome 8 inversion was similar to the frequency of 11.4% previously estimated by the human/hamster-fusion method. For chromosome 1 inversion, the recombination frequency of 0. 4% reported here was below the limits of detection of the fusion technique. The simplicity of the FISH technique and the ease of scoring facilitate analysis of a sample-population size much larger than previously had been possible.

The role of nutrition and diet in rheumatoid arthritis

Given the lack of understanding of the nutritional requirements in RA, plus the variability in its clinical course, it is difficult to produce specific dietary recommendations for RA. In general, sufferers should consume as varied a diet as possible, based on current Department of Health (1991) guidelines. Dietary counselling is important to help patients achieve this. Self-imposed elimination diets should be avoided and suspected food intolerance tested under strict clinical supervision. Nutrient megadosing is inadvisable, although dietary supplementation with Ca, vitamin D, folic acid or multivitamins and minerals should be recommended where necessary.

Genetics of human sperm

PURPOSE

Chromosome abnormalities in sperm were studied by fluorescence in situ hybridization to determine the frequency and distribution of abnormalities in normal men and the effect of donor age on the frequency of abnormalities. Studies of chemotherapy and infertility patients assessed any increased risk in these populations.

METHODS

Multicolor fluorescence in situ hybridization was performed on the sperm samples to assess aneuploidy frequencies for chromosomes 1, 2, 4, 9, 12, 13, 15, 16, 18, 20, 21, X, and Y as well as "sex ratios" and frequencies of diploid sperm.

RESULTS

Most chromosomes yielded disomy estimates of approximately 0.1%, whereas the frequencies for chromosome 21 and the sex chromosomes were significantly elevated. The only chromosome to show a significant paternal age effect was YY disomy. Chemotherapy patients did not have an increased risk of aneuploid sperm 2-13 years after treatment. Infertility patients had an increased risk of disomy for chromosome 1, 13, 21, and XY.

CONCLUSIONS

Multicolor fluorescence in situ hybridization analysis allows comparison of sperm from various populations of men and has demonstrated that infertile patients have a significant increase in the frequency of aneuploid sperm.

Analysis of human sperm karyotypes in testicular cancer patients before and after chemotherapy

Sperm karyotype analysis was performed on testicular cancer patients before and after treatment with BEP (bleomycin, etoposide, and cisplatin). A total of 788 sperm chromosome complements was studied, 236 before chemotherapy (CT) and 552 post-CT. There was no significant difference in the total frequency of sperm chromosomal abnormalities pre-CT (10.2%) compared to post-CT (10.7%). Similarly, there were no significant differences in the frequencies of numerical abnormalities (2.5% pre-CT vs. 2.4% post-CT) or structural abnormalities (6.4% pre-CT vs. 7.4% post-CT). The percentage of X-bearing sperm was also not significantly different before (46.3%) and after CT (50.1%). The results in cancer patients were not significantly different from those in control donors. This study corroborates results from our previous analysis of these same men using multicolor fluorescence in situ hybridization for assessment of aneuploidy for chromosomes 1, 12, X, Y, and XY. Together, these two studies suggest that the sperm of men receiving BEP chemotherapy are not at increased risk of chromosomal abnormalities two or more years after treatment.

Chromosomal abnormalities in sperm from testicular cancer patients before and after chemotherapy

Sperm chromosome abnormalities were assessed in testicular cancer patients before and after treatment with BEP (bleomycin, etoposide, cisplatin). The frequencies of disomy for chromosomes 1, 12, X, Y and XY were assessed along with diploid frequencies and sex ratios by multicolour fluorescence in situ hybridization (FISH). For each cancer patient, a minimum of 10,000 sperm was assessed for each chromosome probe before and after chemotherapy (CT). Data was analysed "blindly" by coding the slides. A total of 161097 sperm were analyzed, 80,445 before and 80,642 after treatment. The mean disomy frequencies were 0.11% pre-CT vs 0.06% post-CT for chromosome 1, 0.18% vs 0.15% for chromosome 12, 0.10% vs 0.9% for the X chromosome, 0.13% vs 0.10% for the Y chromosome and 0.25% vs 0.20% for XY sperm. There was no significant difference in the frequency of disomy pre-CT vs post-CT for any chromosome except that chromosome 1 demonstrated a significant decrease after CT. The "sex ratios" and frequency of diploid sperm were also not significantly different in pre and post-CT samples with 50.2% X-bearing sperm pre-CT and 50.5% X post-CT and 0.14% diploid sperm pre-CT vs 0.15% diploid sperm post-CT. There was no significant donor heterogeneity among the cancer patients. None of the values in the cancer patients differed significantly from 10 normal control donors. Thus our study suggests that BEP chemotherapy does not increase the risk of numerical chromosomal abnormalities in human sperm.

Multicolor fluorescence in situ hybridization analysis of aneuploidy and diploidy frequencies in 225,846 sperm from 10 normal men

Aneuploidy and diploidy frequencies for chromosomes 1, 12, X, and Y were assessed in 225,846 sperm from 10 normal men. Results from 5 of the men have previously been reported. Multicolor fluorescence in situ hybridization (FISH) was used to control for lack of probe hybridization and to distinguish diploidy from disomy. A minimum of 10,000 sperm per donor were evaluated for each chromosome. Sperm were considered disomic if two fluorescent signals were separated by a distance of a minimum of one signal domain. The mean frequencies of disomic sperm for chromosomes 1 and 12 were 0.11% (range 0.05-0.18%) and 0.16% (range 0.10-0.25%), respectively. The means for the sex chromosomal aneuploidies were 0.07% XX, 0.18% YY, and 0.16% XY, totaling 0.42% for all sex chromosomes (range 0.23-0.71%). The incidence of disomic sperm for the sex chromosomes was significantly increased compared to the frequency for the autosomes, corroborating results obtained from studies of sperm karyotypes and spontaneous abortions. The mean frequencies of single X- and Y-bearing sperm were 50.1% and 49.0%, respectively--not significantly different from 50%. The mean frequency of diploid sperm was 0.16% (0.06-0.42%). Interdonor heterogeneity was found to exist for disomy 1, XX, YY, and diploidy, suggesting significant variation among normal men. Comparison of these FISH results to our historical sperm karyotypes demonstrated that the sex ratios and disomy frequencies for chromosomes 1 and X were similar. However, there was a significantly increased frequency of disomic sperm for chromosomes 12, YY, and XY in FISH data compared with sperm karyotypes. In general, FISH data agreed quite well with values from sperm karyotyping, including the increased frequency of sex chromosomal aneuploidy compared with autosomal aneuploidy in sperm. Multicolor FISH analysis permits an accurate distinction between disomic and diploid sperm and allows analysis of large sample sizes. This powerful technology may be useful for future studies of potential environmental and occupational mutagens.

Aneuploidy in human sperm: the use of multicolor FISH to test various theories of nondisjunction

While it is known that all chromosomes are susceptible to meiotic nondisjunction, it is not clear whether all chromosomes display the same frequency of nondisjunction. By use of multicolor FISH and chromosome-specific probes, the frequency of disomy in human sperm was determined for chromosomes 1, 2, 4, 9, 12, 15, 16, 18, 20, and 21, and the sex chromosomes. A minimum of 10,000 sperm nuclei were scored from each of five healthy, chromosomally normal donors for every chromosome studied, giving a total of 418,931 sperm nuclei. The mean frequencies of disomy obtained were 0.09% for chromosome 1; 0.08% for chromosome 2; 0.11% for chromosome 4; 0.14% for chromosome 9; 0.16% for chromosome 12; 0.11% for chromosomes 15, 16, and 18; 0.12% for chromosome 20; 0.29% for chromosome 21; and 0.43% for the sex chromosomes. Data for chromosomes 1, 12, 15, and 18, and the sex chromosomes have been published elsewhere. When the mean frequencies of disomy were compared, the sex chromosomes and chromosome 21 had significantly higher frequencies of disomy than that of any other autosome studied. These results corroborate the pooled data obtained from human sperm karyotypes and suggest that the sex chromosome bivalent and the chromosome 21 bivalent are more susceptible to nondisjunction during spermatogenesis. From these findings, theories proposed to explain the variable incidence of nondisjunction can be supported or discarded as improbable.

The relationship between paternal age, sex ratios, and aneuploidy frequencies in human sperm, as assessed by multicolor FISH

We studied the frequencies of X- and Y-chromosome-bearing sperm, diploidy and disomy for chromosomes 1, 12, X, and Y in sperm from 10 normal men aged 21-52 years, to determine whether there was any relationship between donor age and any of these variables. Multicolor FISH was used to control for lack of probe hybridization and to distinguish diploid sperm from disomic sperm. A minimum of 10,000 sperm per donor was evaluated for each chromosome, for a total of 225,846 sperm studied. Sperm were considered disomic if two fluorescent signals were separated by a minimal distance of one signal domain. The mean frequencies of X- and Y-bearing sperm were 50.1% and 49.0%, respectively; not significantly different from 50%. There was no correlation between paternal age and "sex ratio" in sperm. Similarly, there was no association between the frequency of diploid sperm (mean, .16%; range, .06-.42%) and donor age. For disomy frequencies, there was no relationship between donor age and disomy 12 (mean, .16%; range, .10%-.25%), XX (mean, .07%; range, .03%-.17%), and XY sperm (mean, .16%; range, .08%-.24%). There was a significant increase in the frequency of YY sperm (P = .04; mean, .18%; range, .10%-.43%) and disomy 1 sperm (P = .01; mean, .11%; range, .05%-.18%) with donor age. In summary, our results do not support a correlation between paternal age and sex ratio or diploidy.

Chromosomal analysis of sperm from men with idiopathic infertility using sperm karyotyping and fluorescence in situ hybridization

OBJECTIVE

To determine if idiopathic infertile men having oligozoospermia, asthenozoospermia, or teratozoospermia have an elevated risk of transmitting chromosomal abnormalities to their offspring.

DESIGN

Sperm chromosomal complements from five somatically normal infertile men were assayed using the human sperm-hamster oocyte fusion system and the disomy frequencies for chromosomes 1, 12, and the sex chromosomes were determined using fluorescence in situ hybridization.

SETTING

Infertile men and normal donors were volunteers in an academic research environment.

PATIENTS

Five men with the appropriate semen characteristics were recruited among patients concerned about their infertility.

INTERVENTIONS

Sperm fused with hamster oocytes resulting in sperm chromosomes or the sperm nuclei were prepared for fluorescence in situ hybridization.

MAIN OUTCOME MEASURE

Structural and numerical abnormalities assessed by sperm karyotypes and the disomy frequency determined by fluorescence in situ hybridization analysis.

RESULTS

The infertile men showed increased frequencies of numerical abnormalities and total abnormalities as determined by sperm karyotyping. Analysis of sperm nuclei by fluorescence in situ hybridization indicated a significant increase in the frequency of disomy for chromosome 1 and XY disomy.

CONCLUSIONS

Sperm from infertile men may contain an increased frequency of chromosomal abnormalities.

Reliability of aneuploidy estimates in human sperm: results of fluorescence in situ hybridization studies using two different scoring criteria

Aneuploidy estimates for chromosomes 1, 12, X, and Y were obtained in human sperm from five donors using multicolor fluorescence in situ hybridization (FISH) analysis. Disomy frequencies were obtained by scoring a minimum of 10,000 sperm for each chromosome probe per donor. This analysis was replicated for two scoring criteria: one used one half of a signal domain as the minimum distance between two signals to be counted as two and thus disomic; the other set one signal domain as the minimum distance between two signals. A total of 120,870 sperm were assessed using one half of a domain as the criterion, and 113,478 were scored using one domain as the criterion. The percentage of disomy for chromosomes 1, 12, X, Y, and XY was 0.18, 0.16, 0.15, 0.19, and 0.25, respectively, using the one-half-domain criterion, and 0.08, 0.17, 0.07, 0.12, and 0.16, respectively, using the one-domain criterion. The percentage of disomy decreased significantly with use of one domain as the minimum distance for signal separation for all chromosomes except for chromosome number 12. These lower disomy frequencies correlated well with frequencies derived from human sperm karyotypes analyzed in our laboratory. This suggests that the fluorescent signals for chromosomes 1, X, and Y split into more than one domain in decondensed interphase sperm, and that the use of the one-half-domain criterion would lead to an overestimate of aneuploidy frequencies. The factors known to affect aneuploidy estimates derived from FISH studies are discussed, and recommendations for stringent scoring criteria are proposed.

Relationship between risk factors, knowledge and preventive behaviour relevant to skin cancer in general practice patients in south Australia

BACKGROUND

There is an 'epidemic' increase in skin cancers worldwide in white-skinned populations. Australia has the highest incidence of skin cancer in the world despite intensive publicity in the last 30 years aimed at prevention.

AIM

This study set out to assess risk factors, knowledge and preventive behaviour relevant to skin cancer in general practice patients in South Australia, and to investigate the relationship between risk, knowledge and behaviour.

METHOD

A questionnaire on skin cancer was distributed to 980 patients aged 16 years and over attending general practitioners' surgeries in South Australia. A total of 810 questionnaires were analysed (83%).

RESULTS

There was a high overall level of knowledge and awareness of skin cancer. However, the majority of respondents were unaware of the risks of blue eyes (87%), fair hair (83%) or red hair (68%). A third of respondents were unaware that having lots of moles and freckles was a risk factor for skin cancer. A considerable minority were unaware of the risk of a fair complexion (26%), getting sunburnt (14%) or prolonged exposure to the sun (11%). Sunscreen cream was the most popular preventive behaviour (use reported by 74%), followed by clothing (54%), shade (16%) and timed sun exposure (13%). The most common number of methods of prevention used was two, but 16% were not able to mention anything that they did to prevent skin cancer. The correlations between presence of risk factors, knowledge and preventive behaviour were poor.

CONCLUSION

There was a high overall level of knowledge and awareness of skin cancer in South Australia but despite intense publicity, important areas of ignorance were still found to exist. The simpler methods of skin cancer prevention appeared to be neglected in favour of sunscreen cream. Those at high risk did not know more about skin cancer and reported doing little more to prevent it than those at low risk. There is a need to target those at high risk for education and screening. General practitioners, with adequate training, could have an important part to play in the primary and secondary prevention of mortality and morbidity from skin cancer.

Analysis of chromosomal abnormalities in human sperm after chemotherapy by karyotyping and fluorescence in situ hybridization (FISH)

The frequency of numerical and structural chromosomal abnormalities was studied in the sperm of a lymphoma patient 3 years after MACOP-B chemotherapy (CT). Sperm karyotyping was performed by fusion of human sperm with hamster oocytes and analysis of 193 Q-banded sperm chromosomes. Multicolor fluorescence in situ hybridization (FISH) was performed on 10,228 sperm for analysis of disomy frequencies for chromosomes 1 and 12 and on 10,664 sperm for chromosomes X and Y. Sperm karyotyping demonstrated numerical abnormalities in 7.3% of the spreads, 6.7% hypohaploid and 0.5% hyperhaploid, giving a conservative estimate of aneuploidy of 1%. Structural chromosomal abnormalities were present in 7.3% of the karyotypes and 0.5% had both numerical and structural abnormalities. Results of FISH analyses yielded disomy frequencies of 0.10%, 0.11%, 0.04%, 0.05%, and 0.18% for chromosomes 1, 12, X, Y, and XY, respectively. The frequency of diploid sperm was 0.09%. The frequency of abnormalities was not significantly increased compared to control donors for any of the studies. Also, the frequencies of X- and Y-bearing sperm did not differ significantly from 50% in the sperm karyotyping or FISH studies.

Aneuploidy in human sperm: results of two-and three-color fluorescence in situ hybridization using centromeric probes for chromosomes 1, 12, 15, 18, X, and Y

To understand the mechanisms that affect aneuploidy, fluorescence in situ hybridization (FISH), using chromosome-specific centromeric probes, was employed to screen a large population of human sperm for numerical errors. To determine the true rate of disomy for chromosomes 1, 12, 15, and 18, two-color FISH was performed, and for the gonosomes, three-color FISH. The use of multiple, differently colored probes allows one to distinguish a true disomic sperm from a diploid cell. A minimum of 10,000 sperm nuclei from each of five donors was scored per set of centromeric probes, giving a total of 165,330 sperm nuclei. The disomy frequencies for autosomes 1, 12, 15, and 18 were found to be similar, with a mean of 0.10% (range, 0.05%-0.16%) for chromosome 1, 0.16% (0.10%-0.25%) for chromosome 12, 0.11% (0.07%-0.20%) for chromosome 15, and 0.11% (0.08%-0.17%) for chromosome 18. For the sex chromosomes, the mean frequency of disomy was found to be 0.43% (range, 0.23%-0.71%), with XX disomy accounting for 0.07% (0.03%-0.10%), YY disomy 0.21% (0.10%-0.43%), and XY disomy 0.15% (0.08%-0.24%). The incidence of disomic sperm for the sex chromosomes was significantly increased, compared to the frequency of disomy for the autosomes (chi 2 = 218.61, P < 0.0001). Diploidy was observed in 0.05%-0.47% of the sperm nuclei counted. Interdonor heterogeneity for disomy frequencies was found to exist for the sex chromosomes and for chromosomes 1 and 15, suggesting significant variation among normal men.

Sperm chromosome complements in a man heterozygous for a reciprocal translocation 46,XY,t(9;13)(q21.1;q21.2) and a review of the literature

Sperm chromosome complements were studied in a man heterozygous for a reciprocal translocation t(9;13)(q21.1;q21.2). A total of 89 spermatozoa were karyotyped after in vitro penetration of hamster eggs. The frequencies of alternate, adjacent 1 and adjacent 2 segregations were 46.9%, 35.8% and 17.3% respectively. For alternate segregation, the number of normal spermatozoa (21) was not significantly different from the number of spermatozoa carrying a balanced form of the translocation (17), as theoretically expected. The proportion of spermatozoa with an unbalanced form of the translocation was 53.1%. There was no evidence for an interchromosomal effect since the frequency of numerical abnormalities (unrelated to the translocation) was within the normal range of control donors. Data from a total of 31 reciprocal translocations studied by sperm chromosomal analysis were reviewed.

Chromosomal breakage in human spermatozoa, a heterozygous effect of the Bloom syndrome mutation

The chromosome complements of 662 spermatozoa produced by the three fathers of individuals with Bloom syndrome (BS) were analyzed to determine whether the BS mutation could affect chromosome segregation and the frequency of aneuploidy in sperm. The frequency of numerical abnormalities was not significantly different from that in normal controls studied in our laboratory, but the frequencies of structural abnormalities were significantly increased in two of the men, 14.3% and 15.9%, versus 8.6% in controls. More striking was the increase in these two men of cells with multiple structural abnormalities: 8.1% and 6.7% with multiple abnormalities, versus 2.3% in controls.

Sperm chromosome complements in a man heterozygous for a reciprocal translocation t(2;3)(q24;p26)

Sperm chromosome complements were studied in a man heterozygous for a reciprocal translocation t(2;3)(q24;p26). This man was identified during a family study after his sister was investigated for amenorrhea. A total of 92 spermatozoa were karyotyped after in-vitro penetration of hamster eggs. The frequencies of alternate, adjacent 1, adjacent 2 and 3:1 segregations were 55.4, 36.1, 7.2 and 1.2% respectively. For alternate segregations, the number of normal spermatozoa (n = 25) was not significantly different from the number of spermatozoa carrying a balanced form of the translocation (n = 21), as theoretically expected. The proportion of spermatozoa with an unbalanced form of the translocation was 44.6%. There was no evidence for an interchromosomal effect since the frequencies of numerical and structural abnormalities (unrelated to the translocation) were within the normal range of control donors.